From what I have figured out, stance dancing is a delicate art. The big thing to think about first is what kind of healer ARE you? If you are whm, you can pay attention, if the tank is taking damage to the point you can hit clerics, throw out a holy or some aero action, then fantastic. What I'd do is wait a bit without healing, observe how the tank damage flows, when you need to heal and get a feel for it (don't let the tank die obviously) before I decide. Always keep regen up on the tank and just make sure to pay attention.
With scholar it's easier, throw a shield out when you know damage will be low, hop stances smack away at the enemies, shield drops, hop back, reshield, restance, unleash hell.
AST, it matters first what stance you are in, and how comfortable you are with understanding your own healing competence over the other healer, or just how good your tank is. If you are in nocturnal, it's much the same as a scholar, pop shield, unleash hell with light speed, hop back out and reshield. In Diurnal, you treat it like a whm, know how far your tank can handle not being healed outside of a token regen or two before you go.